Synthesis of zirconium-based material-coated LiNi _0.8Co _0.2O ₂ cathode using a new coating method

Zr-compound-coated LiNi0.8Co0.2O ₂ is prepared in a single step using a new powder coating process, a modified flame spray pyrolysis method using a water-in-oil emulsion precursor solution. Only the Zr precursor is dissolved in the oil phase and the precursors of LiNi0.8Co0.2O ₂ are dissolved in the water phase. In a flame, precursors in the water phase transform into LiNi0.8Co0.2O ₂ core particles and the Zr precursor in the oil phase transforms into a coating layer on the LiNi0.8Co0.2O ₂ surface. After Zr compound coating, both the electrochemical performance and cycle stability are enhanced because the Zr compound coating layer prevents the oxidation of Ni3+ of LiNi0.8Co0.2O ₂ by acidic electrolyte. Since the Zr compound material is coated to prevent the Li2CO3 formation on the LiNi0.8Co0.2O ₂ surface, the effectiveness of the Zr compound coating in preventing Li2CO3 formation is investigated. After the as-prepared Zr-compound-coated LiNi0.8Co0.2O ₂ particles and bare LiNi0.8Co0.2O ₂ particles were exposed in an air for a month, the changes in morphologies and structures before and after aging were observed by using thermal gravimetric analysis (TGA), scanning electron microscopy (SEM) and X-ray diffraction (XRD). It is confirmed that Zr compound coating effectively reduces the amount of Li2CO3 formation.